Some of this may be relevant if active biodigesters that accept horse remains can be found.

DISPOSAL - BIODIGESTION - THE WAY OF THE FUTURE

 

Biodigestion holds promise for equine disposal. This option should satisfy those who argue the primary way equines can be beneficial to humans after death is as food. The technology is already being used for disposal of diseased livestock, chemically euthanized dogs and cats, and animals killed on roadways. Biodigesters can handle many types of biologic materials, including manure. In addition to a number of other useful by-products, units can be set up to generate electricity from the produced methane. The USDA has issued a number of Rural Energy for America Program (REAP) Grants for both research and building plants. Much more information is available online.